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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, linux-mm@kvack.org,
	minchan@kernel.org, mm-commits@vger.kernel.org,
	sergey.senozhatsky@gmail.com, stable@vger.kernel.org,
	torvalds@linux-foundation.org, wu-yan@tcl.com
Subject: [patch 050/118] zsmalloc: account the number of compacted pages correctly
Date: Thu, 25 Feb 2021 17:18:31 -0800
Message-ID: <20210226011831.CV7rry-jF%akpm@linux-foundation.org> (raw)
In-Reply-To: <20210225171452.713967e96554bb6a53e44a19@linux-foundation.org>

From: Rokudo Yan <wu-yan@tcl.com>
Subject: zsmalloc: account the number of compacted pages correctly

There exists multiple path may do zram compaction concurrently.
1. auto-compaction triggered during memory reclaim
2. userspace utils write zram<id>/compaction node

So, multiple threads may call zs_shrinker_scan/zs_compact concurrently.
But pages_compacted is a per zsmalloc pool variable and modification
of the variable is not serialized(through under class->lock).
There are two issues here:
1. the pages_compacted may not equal to total number of pages
freed(due to concurrently add).
2. zs_shrinker_scan may not return the correct number of pages
freed(issued by current shrinker).

The fix is simple:
1. account the number of pages freed in zs_compact locally.
2. use actomic variable pages_compacted to accumulate total number.

Link: https://lkml.kernel.org/r/20210202122235.26885-1-wu-yan@tcl.com
Fixes: 860c707dca155a56 ("zsmalloc: account the number of compacted pages")
Signed-off-by: Rokudo Yan <wu-yan@tcl.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/block/zram/zram_drv.c |    2 +-
 include/linux/zsmalloc.h      |    2 +-
 mm/zsmalloc.c                 |   17 +++++++++++------
 3 files changed, 13 insertions(+), 8 deletions(-)

--- a/drivers/block/zram/zram_drv.c~zsmalloc-account-the-number-of-compacted-pages-correctly
+++ a/drivers/block/zram/zram_drv.c
@@ -1081,7 +1081,7 @@ static ssize_t mm_stat_show(struct devic
 			zram->limit_pages << PAGE_SHIFT,
 			max_used << PAGE_SHIFT,
 			(u64)atomic64_read(&zram->stats.same_pages),
-			pool_stats.pages_compacted,
+			atomic_long_read(&pool_stats.pages_compacted),
 			(u64)atomic64_read(&zram->stats.huge_pages),
 			(u64)atomic64_read(&zram->stats.huge_pages_since));
 	up_read(&zram->init_lock);
--- a/include/linux/zsmalloc.h~zsmalloc-account-the-number-of-compacted-pages-correctly
+++ a/include/linux/zsmalloc.h
@@ -35,7 +35,7 @@ enum zs_mapmode {
 
 struct zs_pool_stats {
 	/* How many pages were migrated (freed) */
-	unsigned long pages_compacted;
+	atomic_long_t pages_compacted;
 };
 
 struct zs_pool;
--- a/mm/zsmalloc.c~zsmalloc-account-the-number-of-compacted-pages-correctly
+++ a/mm/zsmalloc.c
@@ -2212,11 +2212,13 @@ static unsigned long zs_can_compact(stru
 	return obj_wasted * class->pages_per_zspage;
 }
 
-static void __zs_compact(struct zs_pool *pool, struct size_class *class)
+static unsigned long __zs_compact(struct zs_pool *pool,
+				  struct size_class *class)
 {
 	struct zs_compact_control cc;
 	struct zspage *src_zspage;
 	struct zspage *dst_zspage = NULL;
+	unsigned long pages_freed = 0;
 
 	spin_lock(&class->lock);
 	while ((src_zspage = isolate_zspage(class, true))) {
@@ -2246,7 +2248,7 @@ static void __zs_compact(struct zs_pool
 		putback_zspage(class, dst_zspage);
 		if (putback_zspage(class, src_zspage) == ZS_EMPTY) {
 			free_zspage(pool, class, src_zspage);
-			pool->stats.pages_compacted += class->pages_per_zspage;
+			pages_freed += class->pages_per_zspage;
 		}
 		spin_unlock(&class->lock);
 		cond_resched();
@@ -2257,12 +2259,15 @@ static void __zs_compact(struct zs_pool
 		putback_zspage(class, src_zspage);
 
 	spin_unlock(&class->lock);
+
+	return pages_freed;
 }
 
 unsigned long zs_compact(struct zs_pool *pool)
 {
 	int i;
 	struct size_class *class;
+	unsigned long pages_freed = 0;
 
 	for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
 		class = pool->size_class[i];
@@ -2270,10 +2275,11 @@ unsigned long zs_compact(struct zs_pool
 			continue;
 		if (class->index != i)
 			continue;
-		__zs_compact(pool, class);
+		pages_freed += __zs_compact(pool, class);
 	}
+	atomic_long_add(pages_freed, &pool->stats.pages_compacted);
 
-	return pool->stats.pages_compacted;
+	return pages_freed;
 }
 EXPORT_SYMBOL_GPL(zs_compact);
 
@@ -2290,13 +2296,12 @@ static unsigned long zs_shrinker_scan(st
 	struct zs_pool *pool = container_of(shrinker, struct zs_pool,
 			shrinker);
 
-	pages_freed = pool->stats.pages_compacted;
 	/*
 	 * Compact classes and calculate compaction delta.
 	 * Can run concurrently with a manually triggered
 	 * (by user) compaction.
 	 */
-	pages_freed = zs_compact(pool) - pages_freed;
+	pages_freed = zs_compact(pool);
 
 	return pages_freed ? pages_freed : SHRINK_STOP;
 }
_


  parent reply index

Thread overview: 123+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-26  1:14 incoming Andrew Morton
2021-02-26  1:15 ` [patch 001/118] mm: make pagecache tagged lookups return only head pages Andrew Morton
2021-02-26  1:15 ` [patch 002/118] mm/shmem: use pagevec_lookup in shmem_unlock_mapping Andrew Morton
2021-02-26  1:15 ` [patch 003/118] mm/swap: optimise get_shadow_from_swap_cache Andrew Morton
2021-02-26  1:15 ` [patch 004/118] mm: add FGP_ENTRY Andrew Morton
2021-02-26  1:15 ` [patch 005/118] mm/filemap: rename find_get_entry to mapping_get_entry Andrew Morton
2021-02-26  1:15 ` [patch 006/118] mm/filemap: add helper for finding pages Andrew Morton
2021-02-26  1:15 ` [patch 007/118] mm/filemap: add mapping_seek_hole_data Andrew Morton
2021-02-26  1:15 ` [patch 008/118] iomap: use mapping_seek_hole_data Andrew Morton
2021-02-26  1:15 ` [patch 009/118] mm: add and use find_lock_entries Andrew Morton
2021-02-26  1:16 ` [patch 010/118] mm: add an 'end' parameter to find_get_entries Andrew Morton
2021-02-26  1:16 ` [patch 011/118] mm: add an 'end' parameter to pagevec_lookup_entries Andrew Morton
2021-02-26  1:16 ` [patch 012/118] mm: remove nr_entries parameter from pagevec_lookup_entries Andrew Morton
2021-02-26  1:16 ` [patch 013/118] mm: pass pvec directly to find_get_entries Andrew Morton
2021-02-26  1:16 ` [patch 014/118] mm: remove pagevec_lookup_entries Andrew Morton
2021-02-26  1:16 ` [patch 015/118] mm,thp,shmem: limit shmem THP alloc gfp_mask Andrew Morton
2021-02-26  1:16 ` [patch 016/118] mm,thp,shm: limit gfp mask to no more than specified Andrew Morton
2021-02-26  1:16 ` [patch 017/118] mm,thp,shmem: make khugepaged obey tmpfs mount flags Andrew Morton
2021-02-26  1:16 ` [patch 018/118] mm,shmem,thp: limit shmem THP allocations to requested zones Andrew Morton
2021-02-26  1:16 ` [patch 019/118] mm: cma: allocate cma areas bottom-up Andrew Morton
2021-02-26  1:16 ` [patch 020/118] mm/cma: expose all pages to the buddy if activation of an area fails Andrew Morton
2021-02-26  1:16 ` [patch 021/118] mm/page_alloc: count CMA pages per zone and print them in /proc/zoneinfo Andrew Morton
2021-02-26  1:16 ` [patch 022/118] mm: cma: print region name on failure Andrew Morton
2021-02-26  1:16 ` [patch 023/118] mm: vmstat: fix NOHZ wakeups for node stat changes Andrew Morton
2021-02-26  1:16 ` [patch 024/118] mm: vmstat: add some comments on internal storage of byte items Andrew Morton
2021-02-26  1:16 ` [patch 025/118] mm/vmstat.c: erase latency in vmstat_shepherd Andrew Morton
2021-02-26  1:16 ` [patch 026/118] mm: move pfn_to_online_page() out of line Andrew Morton
2021-02-26  1:17 ` [patch 027/118] mm: teach pfn_to_online_page() to consider subsection validity Andrew Morton
2021-02-26  1:17 ` [patch 028/118] mm: teach pfn_to_online_page() about ZONE_DEVICE section collisions Andrew Morton
2021-02-26  1:17 ` [patch 029/118] mm: fix memory_failure() handling of dax-namespace metadata Andrew Morton
2021-02-26  1:17 ` [patch 030/118] mm/memory_hotplug: rename all existing 'memhp' into 'mhp' Andrew Morton
2021-02-26  1:17 ` [patch 031/118] mm/memory_hotplug: MEMHP_MERGE_RESOURCE -> MHP_MERGE_RESOURCE Andrew Morton
2021-02-26  1:17 ` [patch 032/118] mm/memory_hotplug: use helper function zone_end_pfn() to get end_pfn Andrew Morton
2021-02-26  1:17 ` [patch 033/118] drivers/base/memory: don't store phys_device in memory blocks Andrew Morton
2021-02-26  1:17 ` [patch 034/118] Documentation: sysfs/memory: clarify some memory block device properties Andrew Morton
2021-02-26  1:17 ` [patch 035/118] mm/memory_hotplug: prevalidate the address range being added with platform Andrew Morton
2021-02-26  1:17 ` [patch 036/118] arm64/mm: define arch_get_mappable_range() Andrew Morton
2021-02-26  1:17 ` [patch 037/118] s390/mm: " Andrew Morton
2021-02-26  1:17 ` [patch 038/118] virtio-mem: check against mhp_get_pluggable_range() which memory we can hotplug Andrew Morton
2021-02-26  1:17 ` [patch 039/118] mm/mlock: stop counting mlocked pages when none vma is found Andrew Morton
2021-02-26  1:17 ` [patch 040/118] mm/rmap: correct some obsolete comments of anon_vma Andrew Morton
2021-02-26  1:17 ` [patch 041/118] mm/rmap: remove unneeded semicolon in page_not_mapped() Andrew Morton
2021-02-26  1:17 ` [patch 042/118] mm/rmap: fix obsolete comment in __page_check_anon_rmap() Andrew Morton
2021-02-26  1:18 ` [patch 043/118] mm/rmap: use page_not_mapped in try_to_unmap() Andrew Morton
2021-02-26  1:18 ` [patch 044/118] mm/rmap: correct obsolete comment of page_get_anon_vma() Andrew Morton
2021-02-26  1:18 ` [patch 045/118] mm/rmap: fix potential pte_unmap on an not mapped pte Andrew Morton
2021-02-26  1:18 ` [patch 046/118] mm: zswap: clean up confusing comment Andrew Morton
2021-02-26  1:18 ` [patch 047/118] mm/zswap: add the flag can_sleep_mapped Andrew Morton
2021-02-26  1:18 ` [patch 048/118] mm: set the sleep_mapped to true for zbud and z3fold Andrew Morton
2021-02-26  1:18 ` [patch 049/118] mm/zsmalloc.c: convert to use kmem_cache_zalloc in cache_alloc_zspage() Andrew Morton
2021-02-26  1:18 ` Andrew Morton [this message]
2021-02-26  1:18 ` [patch 051/118] mm/zsmalloc.c: use page_private() to access page->private Andrew Morton
2021-02-26  1:18 ` [patch 052/118] mm: page-flags.h: Typo fix (It -> If) Andrew Morton
2021-02-26  1:18 ` [patch 053/118] mm/dmapool: use might_alloc() Andrew Morton
2021-02-26  1:18 ` [patch 054/118] mm/backing-dev.c: " Andrew Morton
2021-02-26  1:18 ` [patch 055/118] mm/early_ioremap.c: use __func__ instead of function name Andrew Morton
2021-02-26  1:18 ` [patch 056/118] mm: add Kernel Electric-Fence infrastructure Andrew Morton
2021-02-26  1:18 ` [patch 057/118] x86, kfence: enable KFENCE for x86 Andrew Morton
2021-02-26  1:19 ` [patch 058/118] arm64, kfence: enable KFENCE for ARM64 Andrew Morton
2021-02-26  1:19 ` [patch 059/118] kfence: use pt_regs to generate stack trace on faults Andrew Morton
2021-02-26  1:19 ` [patch 060/118] mm, kfence: insert KFENCE hooks for SLAB Andrew Morton
2021-02-26  1:19 ` [patch 061/118] mm, kfence: insert KFENCE hooks for SLUB Andrew Morton
2021-02-26  1:19 ` [patch 062/118] kfence, kasan: make KFENCE compatible with KASAN Andrew Morton
2021-02-26  1:19 ` [patch 063/118] kfence, Documentation: add KFENCE documentation Andrew Morton
2021-02-26  1:19 ` [patch 064/118] kfence: add test suite Andrew Morton
2021-02-26  1:19 ` [patch 065/118] MAINTAINERS: add entry for KFENCE Andrew Morton
2021-02-26  1:19 ` [patch 066/118] kfence: report sensitive information based on no_hash_pointers Andrew Morton
2021-02-26  1:19 ` [patch 067/118] tracing: add error_report_end trace point Andrew Morton
2021-02-26 14:03   ` Steven Rostedt
2021-02-26  1:19 ` [patch 068/118] kfence: use error_report_end tracepoint Andrew Morton
2021-02-26  1:19 ` [patch 069/118] kasan: " Andrew Morton
2021-02-26  1:19 ` [patch 070/118] kasan, mm: don't save alloc stacks twice Andrew Morton
2021-02-26  1:19 ` [patch 071/118] kasan, mm: optimize kmalloc poisoning Andrew Morton
2021-02-26  1:20 ` [patch 072/118] kasan: optimize large " Andrew Morton
2021-02-26  1:20 ` [patch 073/118] kasan: clean up setting free info in kasan_slab_free Andrew Morton
2021-02-26  1:20 ` [patch 074/118] kasan: unify large kfree checks Andrew Morton
2021-02-26  1:20 ` [patch 075/118] kasan: rework krealloc tests Andrew Morton
2021-02-26  1:20 ` [patch 076/118] kasan, mm: fail krealloc on freed objects Andrew Morton
2021-02-26  1:20 ` [patch 077/118] kasan, mm: optimize krealloc poisoning Andrew Morton
2021-02-26  1:20 ` [patch 078/118] kasan: ensure poisoning size alignment Andrew Morton
2021-02-26  1:20 ` [patch 079/118] arm64: kasan: simplify and inline MTE functions Andrew Morton
2021-02-26  1:20 ` [patch 080/118] kasan: inline HW_TAGS helper functions Andrew Morton
2021-02-26  1:20 ` [patch 081/118] kasan: clarify that only first bug is reported in HW_TAGS Andrew Morton
2021-02-26  1:20 ` [patch 082/118] alpha: remove CONFIG_EXPERIMENTAL from defconfigs Andrew Morton
2021-02-26  1:20 ` [patch 083/118] proc/wchan: use printk format instead of lookup_symbol_name() Andrew Morton
2021-02-26  1:20 ` [patch 084/118] proc: use kvzalloc for our kernel buffer Andrew Morton
2021-02-26  1:20 ` [patch 085/118] sysctl.c: fix underflow value setting risk in vm_table Andrew Morton
2021-02-26  1:20 ` [patch 086/118] include/linux: remove repeated words Andrew Morton
2021-02-26  1:21 ` [patch 087/118] treewide: Miguel has moved Andrew Morton
2021-02-26  1:21 ` [patch 088/118] groups: use flexible-array member in struct group_info Andrew Morton
2021-02-26  1:21 ` [patch 089/118] groups: simplify struct group_info allocation Andrew Morton
2021-02-26  1:21 ` [patch 090/118] kernel: delete repeated words in comments Andrew Morton
2021-02-26  1:21 ` [patch 091/118] MAINTAINERS: add uapi directories to API/ABI section Andrew Morton
2021-02-27 19:18   ` Michael Kerrisk (man-pages)
2021-02-26  1:21 ` [patch 092/118] lib/genalloc.c: change return type to unsigned long for bitmap_set_ll Andrew Morton
2021-02-26  1:21 ` [patch 093/118] string.h: move fortified functions definitions in a dedicated header Andrew Morton
2021-02-26  1:21 ` [patch 094/118] lib: stackdepot: add support to configure STACK_HASH_SIZE Andrew Morton
2021-02-26  1:21 ` [patch 095/118] lib: stackdepot: add support to disable stack depot Andrew Morton
2021-02-26  1:21 ` [patch 096/118] lib: stackdepot: fix ignoring return value warning Andrew Morton
2021-02-26  1:21 ` [patch 097/118] lib/cmdline: remove an unneeded local variable in next_arg() Andrew Morton
2021-02-26  1:21 ` [patch 098/118] include/linux/bitops.h: spelling s/synomyn/synonym/ Andrew Morton
2021-02-26  1:21 ` [patch 099/118] checkpatch: improve blank line after declaration test Andrew Morton
2021-02-26  1:21 ` [patch 100/118] checkpatch: ignore warning designated initializers using NR_CPUS Andrew Morton
2021-02-26  1:21 ` [patch 101/118] checkpatch: trivial style fixes Andrew Morton
2021-02-26  1:21 ` [patch 102/118] checkpatch: prefer ftrace over function entry/exit printks Andrew Morton
2021-02-26  1:21 ` [patch 103/118] checkpatch: improve TYPECAST_INT_CONSTANT test message Andrew Morton
2021-02-26  1:21 ` [patch 104/118] checkpatch: add warning for avoiding .L prefix symbols in assembly files Andrew Morton
2021-02-26  1:22 ` [patch 105/118] checkpatch: add kmalloc_array_node to unnecessary OOM message check Andrew Morton
2021-02-26  1:22 ` [patch 106/118] checkpatch: don't warn about colon termination in linker scripts Andrew Morton
2021-02-26  1:22 ` [patch 107/118] checkpatch: do not apply "initialise globals to 0" check to BPF progs Andrew Morton
2021-02-26  1:22 ` [patch 108/118] init/version.c: remove Version_<LINUX_VERSION_CODE> symbol Andrew Morton
2021-02-26  1:22 ` [patch 109/118] init: clean up early_param_on_off() macro Andrew Morton
2021-02-26  1:22 ` [patch 110/118] init/Kconfig: fix a typo in CC_VERSION_TEXT help text Andrew Morton
2021-02-26  1:22 ` [patch 111/118] fs/coredump: use kmap_local_page() Andrew Morton
2021-02-26  1:22 ` [patch 112/118] seq_file: document how per-entry resources are managed Andrew Morton
2021-02-26  1:22 ` [patch 113/118] x86: fix seq_file iteration for pat/memtype.c Andrew Morton
2021-02-26  1:22 ` [patch 114/118] scripts/gdb: fix list_for_each Andrew Morton
2021-02-26  1:22 ` [patch 115/118] kgdb: fix to kill breakpoints on initmem after boot Andrew Morton
2021-02-26  1:22 ` [patch 116/118] ubsan: remove overflow checks Andrew Morton
2021-02-26  1:22 ` [patch 117/118] initramfs: panic with memory information Andrew Morton
2021-02-26  1:22 ` [patch 118/118] MIPS: make userspace mapping young by default Andrew Morton
2021-02-26 17:55 ` incoming Linus Torvalds
2021-02-26 19:16   ` incoming Andrew Morton

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